Dimensions tolerance for API 5L seamless pipe

a. For outer diameters less than 2 3/8 in (60.3 mm), pipe body diameter tolerance +/-0.5 mm. Pipe end +/- 0.5 mm; Out of Roundness tolerance for pipe body is 0.9 mm (0.036 in), pipe end 0.6 mm (0.024 mm).
b. For OD equal or above 2 3/8 in (60.3) to 24 in (610 mm), (diameter tolerance) for pipe body is +/- 0.0075D, pipe end +/- 0.005D but max to +/- 1.6 mm (0.063mm); Roundness tolerance for pipe body ≤ 0.015D, pipe end ≤ 0.01D.
(In case agreed with manufacturer and client, more strictly tolerances could be applied)
c. For wall thickness
Below than 4 mm (0.0157 in), tolerance +0.6 (0.024 mm), -0.5 mm (0.020 in);
For API 5L seamless steel pipe thickness in 4 mm to 10 mm (0.394 in), +0.150t, -0.125t;
For API seamless pipe thickness 10 mm to 25mm (0.984 in), +/-0.125t;
Wall thickness ≥ 25 mm, +3.7mm or +0.1t (if larger) and -3.0 mm (0.120 in) or -0.1t (if larger).
t for thickness;
d. For straightness, max for full length, tolerance maximum 0.15% of length.
e. Straightness, max deviation for pipe end, shall be ≤ 0.3 mm /m.
f. Length +/- 200 mm for general, +/- 25.4 mm for special.

Seamless steel pipe manufacturing types

API 5L Seamless steel pipe production methods can be divided into: Hot-rolled seamless pipe, Cold drawn (rolled) pipe and tube, Thermal expansion pipe, Cold spinning tube and Squeeze tubes.

Formation – Seamless API steel pipes are made from a round steel billet while welded pies are made from a strip which is rolled and welded. The formation process of seamless pipes involves forging, perforation, rolling, and shaping all at a time. The defects in the steel can be easily eliminated during the rolling process. On the other hand, the formation process of seamed or welded pipes involves bending plates and welding in desired shapes. The process of making welded pipes is less expensive, and hence, the prices are lower. But in terms of performance, seamless ones are way ahead.

Hot Rolled Seamless steel pipe manufacturing process

Hot Rolling Seamless Steel Line Pipe Manufacturing / Production processes
Rolled Round Billets – Examination – Cut Off – Heating – Piercing – Elongation – Slight Tension Reducing – Straightening – Corp End Cutting Off – Visual Inspection – NDT – Hydrostatic Test – Ends Procession – Product Inspection – Painting and Marking – Packing – Warehousing

Cold Drawn (Rolled) seamless steel pipe manufacturing process

Mother pipe (Normally for hot rolled pipe) – Inspection – Annealing – Ends Treatment (Hitting and Drilling hole) – Pickling – Grinding – Phosphorization (Annoit) – Cold Drawn (Rolled) – Degreasing and Cleaning – Heat treatment (Solution treatment) – Straightening – Hydrostatic test – Painting and Marking – Warehousing